Atomizers are used in any number of applications to dispense or discharge fluids. For example, atomizers may be used for discharging fuel oil in an oil burner or boiler. Many different types of atomizers exist, one such type being a swirl atomizer. In swirl atomizers, liquid is generally directed into an atomizing nozzle or device having a swirl chamber. The liquid rotates in the swirl chamber and forms a thin conical sheet. The sheet is then directed via a hole or slot and breaks into ligaments and discrete particles or droplets upon exiting the nozzle. The droplets then mix with combustion air and evaporate and burn in a flame.
It is desired in oil burner applications to achieve an oil mist exiting the nozzle having fine fluid droplets. Decreasing the oil droplet size generally will reduce the unburned fuel carbon particles that contribute to the black opacity emission from the boiler or combustion device. One method for decreasing an atomizer's fluid droplet size is to provide increased liquid pressure to the atomizer. In swirl atomizers, the increased liquid pressure increases the angular velocity of the liquid within the swirl chamber and may result in a thinner film and hence a finer spray. However, typically substantial pressure must be provided to achieve an optimal droplet size. Achieving such high pressure adds significantly to the cost of atomization.
U.S. Pat. No. 5,269,495 to Döbbeling illustrates a high pressure atomizer having a liquid feed annulus, a plurality of straight radial supply ducts, and a turbulence chamber with an exit orifice. The liquid enters the turbulence chamber through the radial supply ducts where it impinges upon liquid entering from an opposing turbulence duct. This impingement creates a shearing action to atomize the liquid. While Döbbeling suggests that the atomizer achieves small droplet sizes, an inlet fluid pressure of approximately 2175 psig is required to do so.
U.S. Pat. No. 6,024,301 to Hurley et al. teaches an atomizer spray plate for discharging fuel oil. The atomizer taught by Hurley includes a cylindrical rear portion having a number of whirl slots to provide fuel oil with rotational energy to a whirl chamber. The atomizer taught by Hurley does not require the substantial inlet pressure of other prior art devices and thus provides a less costly means for atomization. However, the Hurley atomizer does not achieve the fluid droplet sizes provided by the high pressure atomizers.
It is therefore desired to provide an atomizer that provides fine fluid droplet sizes without the necessity for substantial inlet pressure.